Air-cushion control.



B. n. STEVENS. AIR CUSHWN CONTROL.

APPLICATION FILED JAN- 15. 1916.

Patented uly 25, 1916.

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BURT I). STEVENS, OI EVANSTQN, ILLINCIS, ASSIGNOR T0 IiIIEI'ILE PRINTING PRESS & MANUFACTURING COMPANY, OF CHICAGO. ILLINOIS, A CORPORATION OF ILLINOIS.

AIR-CUSHION CONTROL.

Specification of Letters "Patent.

Patented July 25, Mile.

Application filed January 15, 1916. Serial No. 72,198.

To all roll/omit may concern lie it known that I, BURT D. S'rnvnus, a citizen of the United States, residing at l lvanston, in the county of Cook and State of Illinois, have invented certain new and useful Improvements inAir-Cushion C011 trol, of which the following is a specification.

In the operation of printing presses having a reciprocatory bed it is necessary to provide means for gradually stopping the same at the end of its stroke preparatory to a reversal of the direction of movement, as fully set forth in my co-pending application, Serial No. 7227, upon the construction of which application the present invention is an improvement. It has been proposed and has now become customary to employ for this purpose a dash pot mechanism comprising one or more cylinders and a cooperating piston at each end of the press, the air trapped behind the piston serving as a resilient medium to cushion the bed at the end of each stroke and by the rebound to assist in its return. A simple cylinder and piston combination has, however, proved to be objectionable in that the resistance built up by the compression of air in the cylinder does not at all correspond to the conditions present as it increases very slowly at the start and very rapidly at the end, the rapid increase at the end reaching a high point which is far in excess of that which is proper and which occurs at the time when the driving mechanism of the press is at dead ccnte', and, moreover, this resistance is never the same, under given adjustments, at the different speeds oi the press, wherefore it follows that the cushioning e'liect calculated for one sgeed will be entirely unsuited to other speeds, as when starting and slowing down and moving at slow or high speeds.

In the elifort to overcome the dilliculties noted many expedients have been devised such as venting the cylinder when the pres{ sure reaches a predetermined point and also controlling the point at which such relief shall take place by means of a governor under the influence of the bed driving mechanism, such expedients being illustrated for example in Patents Nos. 4,974, 788,931, 914,492, 989,884.

The invention of my aforementioned application went further and provides for the building up of a resistance in the cylinder,

the curve of which corresponds more nearly to ideal conditions required and for the varylng oi such resistance to suit difierent speeds of operation. The present invention also has the same object in view and seeks to obtain the result in a simplified and more eilicient manner. Having these objects in view I provide, according to my former construotion and also according to the present invention, for the gradual building up of the pressure in the ordinary cylinder of the dash-pot mechanism until the bed approaches the end of its stroke and then pro ride for a further and more gradual increment of pressure during the remainder of the stroke and its reversal, thus avoiding the excess resistance or peak and yet not unduly cutting it down by venting the cylinder. I moreover so connect the device with the governor mechanism as to vary the rate of this final increase of resistance with changes in speed of operation whereby to bring about substantially ideal conditions.

In both the formerand the present conand I control the pressure in such primary reservoirs by connecting them to a common secondary reservoir for air under a degree of pressure which is automatically controlled by the speed of the press. In the former construction, however, the pressure in the secondary reservoir was maintained by a pump, whereas in the present construction, the air is supplied thereto from the dash pot cylinder thus greatly simplifying the construction and adding to its e'lliciency.

In order that the invention and the manner of its application may be readily ap parent, a preferred embodiment of the same is set forth in the accompanying drawings and in the description based thereon. -As, however, the invention is not confined to the particular embodiment set forth, the drawing and description are to be taken in an illustrative and not in an unnecessarily limiting sense.

In the drawing is shown in diagrammatic. manner partly in horizontal section and partly in side elevation one application of the invention to a reciprocating bed of a printing press.

Herein the outline of the bed is indicated in dotted lines at 1, while 2 indicates ribs depending from the lower side of the bed and having rigidly affixed thereto pistons arranged in pairs 33 and 1-4 arranged as the bed is reciprocated to cooperate respectively with the cylinders 55 and 6-6,

which cylinders are suitably supported in a rigid manner. Each of the cylinders has a longitudinal bore divided into two portions 7 and 8 of dissimilar cross sectional area, the bore portion 7 having a diameter corresponding to that of the piston head and having a length slightly greater than the stroke of the piston, the bore 7 thus corresponding t5 the usual cylinder employed for cushioning purposes. lVithin the enlarged bore portion 8 is fitted a disk 9 which bears forwardly against the shoulder 10 and serves as a rear end wall of the cylinder separating the bore portion 7 from. the bore portion 8 which latter forms the primary reservoir for the body of compressed air acting as a cushion against the rear face of the disk 9. The disk 9 has a reduced portion 9 which enters the bore7 to a point slightly spaced from the point reached by the face of the piston at the limit of its stroke.

Where, as is usual, a plurality of cylinders and pistons are employed, I arrange for the control of the pressure within each of the reservoirs 8 by connecting all of said reservoirs through the pipes 11, 12, 13, and 14 to a common secondary reservoir 15 which is supplied with air under pressure through the pipes 16, 17, provided with check valves 18, which pipes 16, 17 are tapped from the bores 7 of the cylinders 5 and 6 respectively at points 19 and 20 immediately adjacent the face of the reduced disk portion 9 In order to prevent an excess of pressure in the reservoir 15 and to vary the maximum pressure to correspond to the feed of the press I provide the said reservoir with a puppet valve 21 of the safety type having mounted upon its arm 22 thecweight 23 which is connected by means of the rod 24, the angle lever 25, the link 26, and the lever 27, with the governor 28, which latter is driven by the bed driving mechanism. It will be obvious that instead of connecting all of the primary compressed air reservoirs 8 with the common secondary reservoir 15, the pressure in which latter is controlled by the governor 28, each of the primary reservoirs 8 may be controlled directly from the governor by providing each with the puppet release valve 21.

It will be understood that the pipes 16 and 17 are of such small capacity as to have no appreciable influence on the building up of resistance air pressure in the bores 7 of the cylinder in front of the pistons 3 and ,4,

but they are in the nature of bleeders,

whereby the air pressure is maintained in i the secondary reservoir 15, without the necessity of providing a special pump for the purpose as was contemplated in the construction of my co-pending' application above referred to. It will also be understood that by reason of the excess of surface area of the larger face of the disk 9 over that of the smaller face of the disk 9 a lower degree of pressure per square inch in the primary reservoir 8 and the secondary air reservoir 15 will suifice. to balance the disk 9 against the pressure building up in the bore 7 of the cylinder in front of the piston, whence it follows that in practice a working pressure in the system at 8, 11, 12, 13,14 and 15 may be employed which is less than one-half the maximum pressure required in opposition to the piston.

The operation of the device is briefly as follows: As the piston head 4:, for instance, enters the cylinder 6 the air is compressed within the bore 7 in the usual manner until it reaches a 'degree'of compression equal to that in the compressed air reservoir 8 behind the disk or movable endwall 9, 9? and tank 15 whereupon any further movement of the piston head 4 and consequent increase of pressure in thebore 7 will cause the check valve 18 to open and a limited amount of air, depending upon'the size of the pipe 17, to pass into the tank 15. The degree of compression within the bore 7 will continue to increase in the usual manner until such time as the total pressure exerted against the wall 9 is equal to the total pressure exerted against the wall 9 by the air in'the chamber 8 and the tank 15 whereupon any I further movement of the piston head 4; and consequent further increase of the pressure in the bore 7 will cause the walls 9-9 to move to the rear resisted by the pressure of the air in the reservoirs 8 and 15. The capacity and cross sectional area of these reservoirs singly'and in the aggregate being in excess of that of the bore 7, thereis but a slight increment of the pressure between the piston head 4 and the disk 9, 9* after the latter begins to move, and the curve of pressure defining the increase of resistance during the final movement of the piston in one direction and its initial movement in the return direction is made to correspond very sure curve takes place being advantageously delayed at high speed and the rate of increase being quickened under such circumstances. This control is provided for by the puppet valve 21 and its connection with the governor whereby the pressure within the reservoir 8 or 15 is permitted to rise higher at a high speed before the puppet valve relieves the pressure therein.

Obviously the invention is not confined to specific details of construction such as those illustrated for descriptive purposes, it being non essential for instance, that the check valve to control the communication between the cylinder 7 and the reservoir 8 be in the form of the disk 9, 9 which as shown constitutes the entire end wall of the cylinder, or a valve controlling a port in the wall of the cylinder and thus forming a portion only of the wall, or an equivalent member arranged in a pipe connecting the cylinder and reservoir, the ei'l'ect being the same in that when a degree of air compression in 7 behind the piston is reached which'balances the air pressure maintained in the reservoirs S and 15, the capacity of the reservoirs is added to that remaining in the closed end of the cylinder, and the subsequent increase of resistance behind the piston is quite gradual as compared with what it would be if such combining of the two spaces were not made, whereby the usual shock at the time of stopping and reversing under high speed is eliminated.

I claim:

1. In an air cushioning device, the combination with a reciprocatory body to be cushioned, and a dash-pot device acting thereon, of a compressed air reservoir, a movable portion of the dash pot wall cushioned by the compressed air in the reservoir, and a bleeder connection leading from the dash pot interior to the reservoir, the two being otherwise out of communication.

2. In an air cushioning device, the combination with a reciprocatory body to be cushioned, and a dash-pot device acting thereon, of a compressed air reservoir, a movable portion of the dash-pot wall cushioned by the compressed air in the reservoir, and a bleeder connection leading from the dash pot interior to the reservoir, the two being otherwise out of communication, and means to vary the pressure of the-air in the reservoir.

3. In an air cushioning device, the combi nation with a reciprocatory body to be cushioned, and a dash-pot device acting thereon, of a con'ipressed air reservoir, a movable portion of the dash pot wall cushioned by the compressed air in the reservoir, and a bleeder connection leading from the dash pot interior to the reservoir, the two being otherwise out of communication, and means controlled by the speed of the reciprocatory body to vary the pressure of the air in the reservoir.

4. In an air cushioning device, the combination with a reciprocatory body to be cushioned, and a dash-pot device acting thereon, of a compressed air reservoir having a greater capacity than that of the dash pot, a movable portion of the dash pot wall cushioned by the compressed air in the reservoir, and a bleeder connection leading from th dash pot interior to the reservoir, the two being otherwise out of communica tion.

In an air cushioning device, the combination with a reciprocatory body to be cushioned, and a dash-pot device acting thereon, of a compressed air reservoir having a greater capacity than tl at of the dash pot, a movable portion of the dash pot wall cushioned by the compressed air in the reservoir, and a bleeder connection leading from the dash pot interior to the reservoir, the two being otherwise out of communication, and means controlled by the speed of the reciprocatory body to vary the pressure of the air in the reservoir.

6. In an air cushioning device, the combination with a reciprocatory body to be cushioned, and a dash-pot device acting thereon, of a compressed air reservoir, a movable portion of the dash pot wall cushioned by the compressed air in the reservoir, the movable portion of the said wall having a greater surface area exposed to the reservoir than to the dash pot interior, and a bleeder connection leading from the interior of the dash pot to the reservoir, the two being otherwise out of communication.

7. In an air cushioning device, the combination with a reciprocatory body to be cushioned, and a dash-pot device acting thereon, of a compressed air reservoir, a movable portion of the dash pot wall cushioned by the compressed air in the reservoir, the movable portion of the said wall having a greater surface area exposed to the reservoir than to the dash pot interior, a bleeder connection leading from the interior of the dash pot to the reservoir, the two being otherwise out of communication, and means controlled by the speed of the reciprocatory body to vary the pressure of the air in the reservoir.

8. In an air cushioning device, the combination with a reciprocatory body to be cushioned, and a cooperating cylinder and piston acting thereon, the bore of the cylinder comprising two portions of diiferent cross sectional area, a movable disk in the larger bore portion and having a smaller bore portion guided within and forming the end wall of the smaller bore portion traversed by the piston, the smaller bore and piston forming a dash pot and the larger bore portion forming at the rear of the disk a compressed air reservoir, a bleeder connection leading from the interior of the dash pot to the reservoir, the two being otherwise out of communication. 7

9. In a air cushioning device, the combination with a reciprocatory body to be cushioned, and a cooperating cylinder and piston acting thereon, the bore of the cylinvary the pressure of the air in the reservoir.

10. In an air cushioning device, the combination with a reciprocatory body to be cushioned, and .a' cooperating cylinder and piston acting thereon, the bore of the cylinder comprising two portions of difierent cross sectional area, a movable disk in the larger bore portion and having a smaller bore portion guided within and forming the end wall of the smaller bore portion traversed by the piston, the smaller bore and piston forming a dash pot and the larger bore portion forming at the rear of thedisk a compressed air reservoir, a bleeder connection leading from the interior of the dash pot to the reservoir, the two being otherwise out of communication, and means controlled by the speed of the reciprocatory body to vary the pressure'of the air in the reservoir, said means comprising a puppet valve arranged to relieve the pressure in the reservoir, a weight varying the action of the valve, a governor influenced by the speed of the reciprocatory body, and a connection between the governor and the weight whereby to vary the maximum pressure of the air with the speed of the body.

I 11. In an air cushioning device, the combination with a reciprocatory body to be cushioned, cooperating cylinders and pistons acting thereon, the bore of each cylinder comprising two portions of different cross sectional area, a movable disk in the larger bore portion and having a smaller portion guided within and forming the end wall of the smaller bore portion traversed by the piston, the smaller bore and piston forming a dash pot and the larger bore portion forming at the rear of the disk a primary compressed air reservoir, a secondary compressed air reservoir connected with all of the primary reservoirs, and a bleeder connection leading from the interior of the smaller bore portion of each of the cylinder to the secondary reservoir, the two being otherwlse out of communication.

12. In an air cushioning device, the comcushioned, cooperating cylinders and pistons acting thereon, the bore of each cylinder comprising two portions of different cross sectional area, a movable disk in the larger bore portion and having a smaller portion guided within and forming the end wall of the smaller bore portion traversed by'the piston, the smaller'bore and piston forming a dash pot and the larger bore portion forming at the rear of the disk a primary compressed air reservoir, a secondary compressed airre'servoir connected with all or" the primary reservoirs, and a bleeder connection leading from the interior of the smallerbore portion of each of the cylinders to thesecondary reservoir, the two being otherwise out of communication, and means controlled by the speed of the reciprocatory body to vary the pressure, of the air in the secondary reservoir.

13. In an air cushioning device, the combination with a reciprocatory body to be obination with a reciprocatory body to be cushioned, cooperating cylinders and pistons acting thereon, the bore of each cylinder comprising two portions of difiierent cross sectional area, a movable disk in the larger bore portion and having -a smaller portion guided within and forming the end wall of the smaller bore portion traversed by the piston, the smaller bore and piston forminga dash pot and the larger boreportion forming at the rear of the disk a primary compressed air reservoir, a secondary compressed air reservoir connected with all of the primary reservoirs, and a bleeder connection leading from the interior of the smaller bore portion of each of the cylinders to the secondary reservoir, the two being otherwise out of communication, and means controlled by the speed of the reciprocatory body to vary the pressure of the air in the secondary reservoir, said means comprising a puppet valve arranged to relieve the pressure in the reservoir, a weight varying the action of the valve, a governor influenced by thespeed of the reciprocatory body, and a connection between the governor and the weight whereby to vary the maximum pressure of the air with the speed of the body. BURT D. STEVENS. Witnesses:

MILTON T. MILLER, Lnwrs T. GREIs'r.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

. Washington, I). 0. I 

